After Nxd4 and Nc3, you can usually play Be3, Qd2, O-O-O against anything (possibly with f3 to prevent Ng4). This is called the English System or the English Attack. It's a bit more risky when black doesn't play ...d6, though.
You can do this in the Nimzowitsch variation of the Petroff, too. (1. e4 e5 2. Nf3 Nf6 3. Nxe5 d6 4. Nf3 Nxe4 5. Nc3)
i hate castling kingside in a sicilian. it feels dull and like a losing position half of the time... after 1.e4 c5 2. nf3 nc6 3. d4 cxd4 4. nxd4 qc7..... what is the best move order for castling queenside? and what are some good ways to defend it?...